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Multi-purpose digital unit C-2

Multi-purpose digital unit C-2 is implemented as IBM PC compatible ISA extension, based on DSP TMS320c549. Unit provides two phone-line interfaces (FXO), two phone interfaces (FXS) and handset interface. The main unit purpose is to serve as hardware base for real time data processing multichannel system.

It is possible to use unit C-2 to build multichannel IP-phone systems, digital voice recorders, auto-answer phone information services, intellectual automatic answering machines, voice mail and fax systems, and other devices with phone interface on the one side and computer features on the other.

This unit is used to build twochannel IP-phone system.

Unit description.

Unit C-2 is implemented as IBM PC compatible ISA extension. Card size is 235 x100. Unit block diagram is shown on the figure below.

There are two phone interfaces FXS to connect two phones (Telephone1 and Telephone2) and two line interfaces FXO to connect two phone lines (Line1 and Line2). MC145567 (Motorola) devices are used as DAC/ADC converters. The main control unit is DSP TMS320VC549 (100 MIPS). There is a RAM 64Kx16 connected to DSP. PLD MAX7128 (Altera) device is used to implement the following connections: DSP to FXS and DSP to FXO interfaces, and DSP to ISA interface. Power Supply block provides direct current phone line supply (-48V) and alternating current call ring supply (~75V) for FXS interface. Software controls switching between FXO and FXS interfaces. Host PC software loads DSP firmware via ISA interface.